Groups Threaten Lawsuit to Protect Imperiled Gulf and Mississippi River Species from Bonnet Carré Spillway Impacts

Today, Defenders of Wildlife and Healthy Gulf (formerly Gulf Restoration Network) posted notice of their intent to sue the U.S. Army Corps of Engineers and Mississippi River Commission for violations of the Endangered Species Act in failing to consult with federal wildlife agencies on the consequences of opening the Bonnet Carré Spillway on numerous endangered and threatened species.

The groups seek to compel the federal agencies to evaluate the impact of opening the Spillway, a flood control mechanism on the lower Mississippi River northwest of New Orleans, on protected wildlife and habitat, including five sea turtle species (loggerhead, leatherback, green, Kemp’s ridley and hawksbill), piping plover, red knot, West Indian manatee, Gulf subspecies of Atlantic sturgeon and pallid sturgeon. 

 “The Mississippi River water released by the Bonnet Carré Spillway that created the toxic algae blooms and habitat damage in Southeast Louisiana and along the Mississippi Coast this year is the same water that creates the annual Gulf Dead Zone,” said Cynthia Sarthou, executive director of Healthy Gulf. “Our suit would require the Army Corp to shoulder its obligation to describe the damage this water has done to protected turtles, fish and birds in the estuaries and bay environments affected by the Spillway opening during the 2018-2019 Mississippi River Flood, but this is all part of the same water quality crisis in the Mississippi River Drainage.”

When opened, the Spillway diverts floodwaters from the Mississippi River into the estuary ecosystem of Lake Pontchartrain, Lake Borgne, and the Mississippi Sound in the Gulf of Mexico. The diverted water carries sediment and pollutants, including agricultural fertilizer and pesticide runoff, decreases salinity levels and water temperatures, and causes eutrophication, triggering harmful algal blooms which in turn create hypoxic dead zones (low oxygen areas). Nonetheless, the Army Corps and Mississippi River Commission have never rigorously studied the impacts of opening the Spillway on this ecosystem, imperiled wildlife, or protected habitats as required by the Endangered Species Act.

“Threatened and endangered species still struggling to recover from the Gulf oil spill disaster cannot afford for the Spillway’s previously once-a-decade disruptions to become annual or biannual,” said Defenders attorney Maggie Coulter. “The federal agencies must study how more frequent operation affects imperiled species and their habitat and mitigate those impacts.” 

For the first seven decades since its construction in 1931, the agencies opened the Spillway on average about once per decade. In the last 11 years, they have opened the Spillway six times, including once in 2018 and twice in 2019. The 2018 and 2019 openings were the first time the Spillway had been opened in consecutive years, and the 2019 openings marked the first time the Spillway had ever been opened twice in one year. As more extreme storms and varied weather increase the number and intensity of floods in the Lower Mississippi River Valley region, it is likely that the Spillway will be opened more frequently and for increasingly longer duration—to the continued detriment of endangered and threatened species.

The federal agencies now have 60 days to remedy the alleged violations in order to avoid litigation.